Atari positioned the Assembler Editor as a tool for small projects and learning, primarily because assembly times were extremely slow for anything but the smallest programs. The Atari Macro Assembler (AMAC) was offered by Atari to provide better performance and more powerful features, such as macros, but AMAC was disk-based, copy-protected, and it did not include an editor or debugger.

Upon bootup, the cartridge started up in EDIT mode. The programmer would enter assembly source into the editor using the full-screen features on the Atari. All source had to be prefixed with a line number, or it would be interpreted as a command. Due to limited cartridge space, errors were reported with numeric error codes.

The debugger, really a monitor, was entered by typing in the command BUG at the prompt. The debugger allowed the viewing and changing of registers and memory locations, code tracing, single-step and disassembly.

The programmer went back to the EDIT mode by typing X at the command prompt.

Optimized Systems Software purchased the original rights to the Atari Assembler Editor from Shepardson Microsystems and released improved versions, including EASMD. The Assembler Editor continued to be available from Atari.